1. Field of the Invention
This invention relates to a swinging, spherical gate valve employing compound movement between open and closed positions, and more particularly, to a valve of this type which provides a clean and unrestricted flow path with fast actuation between open and closed positions, and additionally, to the employment of two similar valves to effect a double seal, fluid line disconnect, which couples or disconnects without axial movement.
2. Description of the Prior Art
This invention constitutes an improvement upon my prior U.S. Pat. Nos. 3,498,583 and 3,675,894 directed to swinging gate valves which involve compound movement to effect movement of the valve gate or poppet from an open position to the side of the flow path to a closed position generally at right angles thereto and translated axially relative to a coaxial annular valve seat to effect a sealed closure.
In U.S. Pat. No. 3,675,894, a spherical segment or "eyelid" drops completely out of the flow stream into a spherical pocket in the side of the valve housing. The valve is supported by a rotatable shaft with the shaft in turn being supported by opposed bearings on opposite sides of the valve body such that its axis passes through the center of curvature of the semispherical body. The eyelid rests within the pocket supported on said shaft by rotatable and axially shiftable support links, and a control plate and guide plate controls the extent of angular rotation of the support links and the axial extension of the links and the valve after rotation, to a position coaxially with the flow path, to effect sealing of the eyelid against the circular valve seat. Eccentric means effect axial shifting of the eyelid disc and the support links when the eyelid is coaxially positioned with respect to that valve seat. The eyelid or spherical gate valve common to that patent and this application requires less power to operate, is compact and lighter in weight and capable of very much faster response than the prior art gate and ball valves. Since the eyelid drops out of the flow path in each case, the valves are characterized by small profile, low pressure drop, positive seal engagement between the gate and the valve seat and low leakage. Such valves may be advantageously employed in all areas of fluid handling, particularly high pressure hydraulic control systems. The valves are highly useful in petroleum plants and transport lines using "pigs" or air filled rubber bladders, to isolate various commodities being pumped such as diesel fuel, followed by regular gasoline, and each type is followed by one or more "pigs." Thus, the valve which controls fluid flow through the transport lines must be free of any internal obstructions which impede the travel of or damage to the pig, otherwise, the isolation is lost. Conventional gate or ball valves require high power and most large gate valves have a wide gate slot which is detrimental to the passage of the pig.
One aspect of the present invention is to provide an improved swinging spherical gate valve in which there is no obstruction to flow and no support or drive mechanism extending through the flow stream.
When used in a petroleum plant or transport system, provision must be made for "pig" insertion and retrieval. At the beginning and end of the transport line, as well as at intermediate delivery points, pigs must be inserted or removed from the line. Presently, a flange bolted door is opened in a Y branch, the pig is inserted, and the door bolt is shut. The valve is open at the time of the commodity change and the pig is blown into the main line by compressed air, separating the two commodities.
Another aspect of the present invention is to provide an improved swinging spherical gate valve employable in a petroleum plant or liquid transport system, which eliminates the necessity for a second main valve and which provides ready access to the flow path in a fast and expeditious manner.
Where the petroleum transport system is of the type such as the Trans-Alaska Pipeline and the pipeline is of high concern to ecologists and environmentalists, not only from the standpoint of the heat of the oil and mounting on the permafrost, but is also of great concern in terms of the possibilities of ruptures and vast oil spills, such lines of necessity will utilize huge pigs to isolate commodities, primarily crudes from various participating companies. The present invention, therefore, has additional use as a remote control or automatic safety valve in the event of break or rupture with the valve.
In the cryogenic and vacuum field, there exists the necessity for providing a coupling between line sections characterized by positive seal engagement and low leakage and wherein both portions the coupling of respective line sections carry valves which insure line section sealing prior to disconnect.
The present invention, when employing two identical valves except for locating and locking interface, provides face to face coupling permitting coupling or disconnect without axial movement, and the invention is characterized by an improved, overcenter cam lock clamping mechanism to achieve this end.